Late cardiac remodeling after primary percutaneous coronary intervention-five-year cardiac magnetic resonance imaging follow-up.

BACKGROUND: Primary percutaneous coronary intervention (PPCI) preserves function and improves survival. The late effects of PPCI on left ventricular remodeling, however, have not yet been investigated on cardiac magnetic resonance imaging (CMRI). METHODS AND RESULTS: Twenty-five patients with acute myocardial infarction (AMI) treated with PPCI underwent CMRI within 10 days, at 4 months and at 5 years. Left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume were quantified on cine images. Infarct mass and transmural extent of infarction were quantified on contrast-enhanced imaging. In all patients EDV increased significantly in the early phase (192 ± 40 ml to 211 ± 49 ml, P ≤ 0.01) and LVEF improved significantly (42 ± 9% to 46 ± 9%, P=0.02). In the late phase (>4 months) no significant changes were observed (LVEF 44 ± 9%, P=0.07; EDV 216 ± 68 ml, P=0.38). Three different groups could be identified. One-third (32%) had no dilatation at all; one-third (32%) had limited dilatation at 4 months without progression later; and 36% had progressive dilatation both at 4 months and at late follow-up. This third group had an average increase in EDV of 20% in the acute phase followed by an additional 13%. The strongest predictor for progressive dilatation was infarct mass. CONCLUSIONS: Even in the era of PPCI for AMI followed by optimal medical therapy, one-third of patients had progressive dilatation, which was best predicted by infarct mass.

Different algorithms for quantitative analysis of myocardial infarction with DE MRI: comparison with autopsy specimen measurements.

RATIONALE AND OBJECTIVES: To compare two semiautomated methods for measurement of infarcted myocardium area on delayed contrast enhanced magnetic resonance imaging, with histopathology findings as standard of reference. MATERIALS AND METHODS: Percentage area of myocardial infarction was measured in 10 Yorkshire landrace pigs manually and using two semiautomated methods. The first (standard deviation method) used two operator-selected regions of interest (ROIs) and nine different cutoff values (one to nine times the standard deviation of signal intensity in normal myocardium) to identify infarction. The second (threshold method) used threshold values based on percentages of maximum signal intensity to identify infarction. Results were compared with histopathology findings. RESULTS: Difference between percentage area of infarction obtained with standard deviation method and autopsy specimens was in the range: -13.5% to +13.2%. With threshold method (thresholds from 30% to 90% of signal intensity), difference was -15% to +23%. Manual contouring underestimated infarcted area by 2% comparing to autopsy results. The best agreement between histopathology and semi-automated software was achieved for 4 standard deviations with standard deviation method: difference -0.45%, and for a percentage threshold of 70% (difference +0.67%) with threshold method. However, with standard deviation method, there was statistically significant difference between ROIs based on their location in viable myocardium: mean difference 1.7 ± 4%, P < .0001. CONCLUSION: Semiautomated measurement of myocardial infarcted area on delayed enhanced magnetic resonance images performs well compared to autopsy. The threshold method, based on percentages of maximum signal intensity is preferable over standard deviation method, which is more susceptible to variability from location of ROIs within viable myocardium.

Computed tomography unmasks a phantom tumour.

We describe a patient with left sided congestive heart failure and a round-shaped mass on the chest X-ray. Using computed tomography, the mass is diagnosed as a phantom tumour consisting of loculated effusion in the interlobular fissure that vanishes after treatment for heart failure is initiated.

Accurate automatic papillary muscle identification for quantitative left ventricle mass measurements in cardiac magnetic resonance imaging.

RATIONALE AND OBJECTIVES: We sought to evaluate the automatic detection of the papillary muscle and to determine its influence on quantitative left ventricular (LV) mass assessment. MATERIALS AND METHODS: Twenty-eight Yorkshire-Landrace swine and 10 volunteers underwent cardiac magnetic resonance imaging (CMR) of the left ventricle. The variability in measurements of LV papillary muscles traced automatically and manually were compared to intra- and interobserver variabilities. CMR-derived LV mass with the papillary muscle included or excluded from LV mass measurements was compared to true mass at autopsy of the Yorkshire-Landrace swine. RESULTS: Automatic LV papillary muscle mass from all subjects correlated well with manually derived LV papillary muscle mass measurements (r = 0.84) with no significant bias between both measurements (mean difference +/- SD, 0.0 +/- 1.5 g; P = .98). The variability in results related to the contour detection method used was not statistically significant different compared to intra- and interobserver variabilities (P = .08 and P = .97, respectively). LV mass measurements including the papillary muscle showed significantly less underestimation (-10.6 +/- 7.1 g) with the lowest percentage variability (6%) compared to measurements excluding the papillary muscles (mean underestimation, -15.1 +/- 7.4 g percentage variability, 7%). CONCLUSION: The automatic algorithm for detecting the papillary muscle was accurate with variabilities comparable to intra- and interobserver variabilities. LV mass is determined most accurately when the papillary muscles are included in the LV mass measurements. Taken together, these observations warrant the inclusion of automatic contour detection of papillary muscle mass in studies that involve the determination of LV mass.

Evaluation of left ventricular function three years after percutaneous recanalization of chronic total coronary occlusions.

We investigated early and late effects of percutaneous revascularization for chronic total coronary occlusion on left ventricular (LV) function and volumes. Magnetic resonance imaging was performed in 21 patients before and 5 months and 3 years after recanalization. Global LV function and volumes and segmental wall thickening (SWT) were quantified on cine images. The 2 viability indexes used were the transmural extent of infarction (TEI) on delayed contrast enhancement images and end-diastolic wall thickness at baseline. Significant decreases in mean end-diastolic (86 +/- 14 to 78 +/- 15 ml/m2; p = 0.02) and mean end-systolic volume indexes (35 +/- 13 to 30 +/- 13 ml/m2; p = 0.03) were observed 3 years after recanalization. Mean ejection fraction tended to improve (60 +/- 9% to 63 +/- 11%; p = 0.11). SWT significantly increased at 5-months' follow-up (p <0.001), and an additional improvement was found at 3 years' (p = 0.04) follow-up in segments with TEI <25%. In segments with TEI of 25% to 75%, SWT was unchanged at 5-month follow-up (p = 0.89), but improved at 3 years (p = 0.04). SWT was unchanged in segments with transmural scars. For segmental functional recovery, TEI was a better predictor than end-diastolic wall thickness at baseline (odds ratio 5.6, 95% confidence interval 1.5 to 21.1, p = 0.01 vs odds ratio 2.5, 95% confidence interval 0.7 to 8.3, p = 0.14). In conclusion, a positive effect on LV remodeling and ejection fraction was observed up to 3 years after recanalization. Both early and late improvements in regional LV function were observed in the perfusion territory of chronic total coronary occlusion and were related to the transmural extent of infarction on pretreatment magnetic resonance imaging.

Addition of the long-axis information to short-axis contours reduces interstudy variability of left-ventricular analysis in cardiac magnetic resonance studies.

OBJECTIVES: To reduce interstudy variability using long-axis information for correcting short-axis (SA) contours at basal and apical level for left-ventricular analysis by magnetic resonance imaging. MATERIALS AND METHODS: A total of 20 patients with documented heart failure and 20 volunteers underwent magnetic resonance imaging examination twice for measuring endocardial end-diastolic volume, endocardial end-systolic volume, mass, and ejection fraction. The boundary of the left ventricle, the mitral valve plane, and apex were marked manually on the 2- and 4-chamber long-axis images. Automatic epicardial and endocardial contour detection was performed on the SA images using the intersection of the outlines from the long axis as starting positions. The same observer compared the interstudy variability of this method with analysis that was based on the SA images only. RESULTS: The interstudy variability decreased when information from the long axis was included; for end-systolic volume, 9.6% versus 4.7% (P = 0.00014); for end-diastolic volume, 4.9% versus 2.5% (P = 0.0011); for mass, 7.4% versus 5.0% (P = 0.11); and for ejection fraction 12.2% versus 5.6% (P = 0.0017), respectively. CONCLUSIONS: Identification of the mitral valve plane and apex on long-axis images to limit the extent of volume at the base and the apex of the heart reduces interstudy variability for left-ventricular functional assessment.

A comparison between QLAB and TomTec full volume reconstruction for real time three-dimensional echocardiographic quantification of left ventricular volumes.

OBJECTIVES: To compare the interobserver variability and accuracy of two different real time three-dimensional echocardiography (RT3DE) analyzing programs. METHODS: Forty-one patients (mean age 56 +/- 11 years, 28 men) in sinus rhythm with a cardiomyopathy and adequate 2D image quality underwent RT3DE and magnetic resonance imaging (MRI) within one day. Off-line left ventricular (LV) volume analysis was performed with QLAB V4.2 (semiautomated border detection with biplane projections) and TomTec 4D LV analysis V2.0 (primarily manual tracking with triplane projections and semiautomated border detection). RESULTS: Excellent correlations (R(2) > 0.98) were found between MRI and RT3DE. Bland-Altman analysis revealed an underestimated LV end-diastolic volume (LV-EDV) for both TomTec (-9.4 +/- 8.7 mL) and QLAB (-16.4 +/- 13.1 ml). Also, an underestimated LV end-systolic volume (LV-ESV) for both TomTec (-4.8 +/- 9.9 mL) and QLAB (-8.5 +/- 14.2 mL) was found. LV-EDV and LV-ESV were significantly more underestimated with QLAB software. Both programs accurately calculated LV ejection fraction (LV-EF) without a bias. Interobserver variability was 6.4 +/- 7.8% vs. 12.2 +/- 10.1% for LV-EDV, 7.8 +/- 9.7% vs. 13.6 +/- 11.2% for LV-ESV, and 7.1 +/- 6.9% vs. 9.7 +/- 8.8% for LV-EF for TomTec vs. QLAB, respectively. The analysis time was shorter with QLAB (4 +/- 2 minutes vs. 6 +/- 2 minutes, P < 0.05). CONCLUSIONS: RT3DE with TomTec or QLAB software analysis provides accurate LV-EF assessment in cardiomyopathic patients with distorted LV geometry and adequate 2D image quality. However, LV volumes may be somewhat more underestimated with the current QLAB software version.

Adjunctive value of CT coronary angiography in the diagnostic work-up of patients with typical angina pectoris.

AIMS: To determine the adjunctive value of CT coronary angiography (CTCA) in the diagnostic work-up of patients with typical angina pectoris. METHODS AND RESULTS: CTCA was performed in 62 consecutive patients (45 male, mean age 58.8 +/- 7.7 years) with typical angina undergoing diagnostic work-up including exercise-ECG and conventional coronary angiography. Only patients with sinus heart rhythm and ability to breath hold for 20 s were included. Patients with initial heart rates >/=70 beats/min received beta-blockers. We determined the post-test likelihood ratios, to detect or exclude patients with significant (>/=50% lumen diameter reduction) stenoses, of exercise-ECG and CTCA separately, and of CT performed after exercise-ECG testing. The prevalence of patients with significant coronary artery disease (CAD) was 74%. Positive and negative likelihood ratios for exercise-ECG were 2.3 [95% confidence interval (CI): 1.0-5.3] and 0.3 (95% CI: 0.2-0.7) and for CTCA 7.5 (95% CI: 2.1-27.1) and 0.0 (95% CI: 0.0-8), respectively. CTCA increased the post-test probability of significant CAD after a negative exercise-ECG from 58 to 91%, and after a positive exercise-ECG from 89 to 99%, while CT correctly identified patients without CAD (probability 0%). CONCLUSION: Non-invasive CTCA is a potentially useful tool, in the diagnostic work-up of patients with typical angina pectoris, both to detect and to exclude significant CAD.

Non-invasive visualization of coronary atherosclerosis: state-of-art.

Coronary artery disease remains the leading cause of death in the Western world. Non-invasive coronary artery imaging challenges any diagnostic modality because the coronary arteries are small and tortuous, whereas cardiac contraction and respiration cause motion artifacts. Therefore, non-invasive coronary imaging requires high spatial and temporal resolution. This review discusses the feasible applications in coronary imaging of magnetic resonance imaging and multi-slice computed tomography (MSCT), which are currently the only non-invasive diagnostic modalities for direct coronary atherosclerosis imaging. Particular attention and focus is devoted to the potential indications and clinical impact of MSCT due to its fast development and the robust results recently reported. MSCT of the coronary arteries is a promising imaging modality for the assessment of the coronary lumen and wall.

Intracoronary delivery of umbilical cord blood derived unrestricted somatic stem cells is not suitable to improve LV function after myocardial infarction in swine.

Regeneration of infarcted myocardium by injecting stem cells has been proposed to prevent heart failure. We studied the i.c. administration of human umbilical cord blood stem cells (USSC) in a porcine model of myocardial infarction (MI) and reperfusion. In 15 swine, MI was induced by balloon-occlusion of the left circumflex coronary artery (LCX) for 2 h followed by reperfusion. Five swine served as healthy controls. One week later, magnetic resonance imaging (MRI) was performed to assess left ventricular (LV) function and infarct size. Then, under immune suppression, 6 of the 12 surviving MI swine received intracoronary injection of approximately 10(8) human USSC in the LCX while the other MI-swine received medium. Four weeks later all swine underwent follow-up MRI, and were sacrificed for histology. One week after MI, end-diastolic volume (92+/-3 mL) and LV mass (75+/-2 g) were larger, while ejection fraction (42+/-2%) was smaller than in healthy control (68+/-3 mL, 66+/-3 g and 55+/-3%, all P<0.05). Regional wall thickening (-7+/-2%) in the LCX area became akinetic. No difference in global and regional LV function at 5 weeks was observed between MI animals receiving USSC or medium. Infarct size after USSC treatment was significantly larger (20+/-3 g vs. 8+/-2 g, P<0.05). USSC survived only in the infarct border zone at 5 weeks and did not express cardiomyocyte or endothelial markers. Histology showed that intracoronary injection of USSC caused micro infarctions by obstructing blood vessels. In swine with a 1 week old MI, injection of USSC via the intracoronary route does not improve LV function 4 weeks later.

Assessment of acute reperfused myocardial infarction with delayed enhancement 64-MDCT.

OBJECTIVE: The purpose of this study was to evaluate the utility of delayed enhancement 64-MDCT in the assessment of myocardial infarct size in a porcine model of acute reperfused myocardial infarction. CT can be used for noninvasive assessment of coronary artery stenosis, but to our knowledge, evaluation of myocardial viability in the subacute phase of acute myocardial infarction has not been validated. We performed delayed enhancement imaging on six domestic swine 5 days after reperfused acute myocardial infarction and assessed the relation between delayed enhancement patterns in vivo and the extent of viable and nonviable myocardium at postmortem histochemical analysis. CONCLUSION: Delayed enhancement imaging with 64-MDCT can be used for accurate assessment of the size of reperfused acute myocardial infarcts.

Reduction in infarct size, but no functional improvement after bone marrow cell administration in a porcine model of reperfused myocardial infarction.

AIMS: Stem cell therapy after myocardial infarction (MI) has been studied in models of permanent coronary occlusion. We studied the effect of intracoronary administration of unselected bone marrow (BM) and mononuclear cells (MNC) in a porcine model of reperfused MI. METHODS AND RESULTS: In 34 swine, the left circumflex coronary artery was balloon-occluded for 2 h followed by reperfusion. Ten swine without MI served as controls. All swine underwent magnetic resonance imaging (MRI) 1 week post-MI. The next day, 10 of the 30 surviving MI swine received BM, 10 other MI swine received MNC, and the remaining MI swine received medium intracoronary. Four weeks later, all swine underwent a follow-up MRI. One week after MI, end-diastolic volume (92+/-16 mL) and left ventricular (LV) weight (78+/-12 g) were greater, whereas ejection fraction (40+/-8%) was lower than in controls (69+/-11 mL, 62+/-13 g, and 53+/-6%). Injection of BM or MNC had no effect on the MI-induced changes in global or regional LV-function. However, there was a significant reduction in infarct size 4 weeks after MNC injection (-6+/-3%) compared with the medium (-3+/-5%). CONCLUSION: Intracoronary injection of BM or MNC in swine does not improve regional or global LV-function 4 weeks after injection. However, a reduction in infarct-size was noted after MNC injection.

Multislice computed tomography and magnetic resonance imaging for the assessment of reperfused acute myocardial infarction.

OBJECTIVES: We evaluated the accuracy of in vivo delayed-enhancement multislice computed tomography (DE-MSCT) and delayed-enhancement magnetic resonance imaging (DE-MRI) for the assessment of myocardial infarct size using postmortem triphenyltetrazolium chloride (TTC) pathology as standard of reference. BACKGROUND: The diagnostic value of DE-MSCT for the assessment of acute reperfused myocardial infarction is currently unclear. METHODS: In 10 domestic pigs (25 to 30 kg), the circumflex coronary artery was balloon-occluded for 2 h followed by reperfusion. After 5 days (3 to 7 days), DE-MRI (1.5-T) was performed 15 min after administration of 0.2 mmol/kg gadolinium-DTPA using an inversion recovery gradient echo technique. On the same day, DE-MSCT (64-slice) was performed 15 min after administration of 1 gI/kg of iodinated contrast material. One day after imaging, hearts were excised, sectioned in 8 mm short-axis slices, and stained with TTC. Infarct size was defined as the hyperenhanced area on DE-MSCT and DE-MRI images and the TTC-negative area on TTC pathology slices. Infarct size was expressed as percentage of total slice area. RESULTS: Infarct size determined by DE-MSCT and DE-MRI showed a good correlation with infarct size assessed with TTC pathology (R2 = 0.96 [p < 0.001] and R(2) = 0.93 [p < 0.001], respectively). The correlation between DE-MSCT and DE-MRI was also good (R2 = 0.96; p < 0.001). The relative difference in CT attenuation value of infarcted myocardium compared to remote myocardium was 191 +/- 18%. The relative MR signal intensity between infarcted myocardium and remote myocardium was 554 +/- 156%. CONCLUSIONS: We demonstrated that DE-MSCT can assess acute reperfused myocardial infarction in good agreement with in vivo DE-MRI and TTC pathology.

Automatic quantitative left ventricular analysis of cine MR images by using three-dimensional information for contour detection.

The purpose of this study was to evaluate an automatic boundary detection algorithm of the left ventricle on magnetic resonance (MR) short-axis images with the essential restriction of no manual corrections. The study comprised 13 patients (nine men, four women) and 12 healthy volunteers (11 men, one woman), and institutional review board approval and informed consent were obtained. The outline of the left ventricle was indicated manually on horizontal and vertical long-axis MR images. The calculated intersection points with the short-axis MR images were the basis of the automatic contour detection. Automatically derived volumes correlated highly with manually derived (short axis-based) volumes (R2 = 0.98); ejection fraction (EF) and mass showed a correlation of 0.95 and 0.93, respectively. Automatic contour detection reduced interobserver variability to 0.1 mL for endocardial end-diastolic and end-systolic volumes, 1.1 mL for epicardial end-diastolic and end-systolic volumes, 0.02% for EF, and 1.1 g for mass. Thus, the algorithm enabled highly reproducible left ventricular parameters to be obtained.

Magnetic resonance imaging of haemorrhage within reperfused myocardial infarcts: possible interference with iron oxide-labelled cell tracking?

AIMS: Magnetic resonance imaging (MRI) has been proposed as a tool to track iron oxide-labelled cells within myocardial infarction (MI). However, infarct reperfusion aggravates microvascular obstruction (MO) and causes haemorrhage. We hypothesized that haemorrhagic MI causes magnetic susceptibility-induced signal voids that may interfere with iron oxide-labelled cell detection. METHODS AND RESULTS: Pigs (n = 23) underwent 2 h occlusion of the left circumflex artery. Cine, T2*-weighted, perfusion, and delayed enhancement MRI scans were performed at 1 and 5 weeks, followed by ex vivo high-resolution scanning. At 1 week, MO was observed in 17 out of 21 animals. Signal voids were observed on T2*-weighted scans in five out of eight animals, comprising 24 +/- 22% of the infarct area. A linear correlation was found between area of MO and signal voids (R2 = 0.87; P = 0.002). At 5 weeks, MO was observed in two out of 13 animals. Signal voids were identified in three out of seven animals. Ex vivo scanning showed signal voids on T2*-weighted scanning in all animals because of the presence of haemorrhage, as confirmed by histology. Signal voids interfered with the detection of iron oxide-labelled cells ex vivo (n = 21 injections). CONCLUSION: Haemorrhage in reperfused MI produces MRI signal voids, which may hamper tracking of iron oxide-labelled cells.

Prediction of left ventricular function after drug-eluting stent implantation for chronic total coronary occlusions.

OBJECTIVES: We studied the effect of drug-eluting stent implantation for chronic total coronary occlusion (CTO) on left ventricular volumes and function and assessed the predictive value of magnetic resonance imaging (MRI) performed before revascularization. BACKGROUND: The effect of recanalization of CTO on long-term left ventricular function and the value of myocardial viability assessment with MRI is incompletely understood. METHODS: Twenty-seven patients underwent contrast-enhanced MRI before and five months after successful drug-eluting stent implantation for CTO. A CTO was defined as a complete occlusion of a major epicardial coronary artery existing for at least six weeks (mean, 7 +/- 5 months). Myocardial wall thickening and left ventricular volumes were quantified on cine-images, and the transmural extent of infarction (TEI) was scored on delayed-enhancement images. RESULTS: A significant decrease in mean end-systolic volume index (34 +/- 13 ml/m2 to 31 +/- 13 ml/m2; p = 0.02) and mean end-diastolic volume index (84 +/- 15 ml/m2 to 79 +/- 15 ml/m2; p < 0.002) was observed, whereas the mean ejection fraction did not change significantly (61 +/- 9% to 62 +/- 11%; p = 0.54). The extent of the left ventricle that was dysfunctional but viable before revascularization was related to improvement in end-systolic volume index (R = 0.46; p = 0.01) and ejection fraction (R = 0.49; p = 0.01) but not to the end-diastolic volume index (R = 0.10; p = 0.53). Segmental wall thickening improved significantly in segments with <25% TEI (21 +/- 15% to 35 +/- 25%; p < 0.001), tended to improve in segments with 25% to 75% TEI (18 +/- 22% to 27 +/- 22%; p = 0.10), whereas segments with >75% TEI did not improve (4 +/- 14% to -9 +/- 14%; p = 0.54). CONCLUSIONS: Drug-eluting stent implantation for a CTO has a beneficial effect on left ventricular volumes and function that can be predicted by performing MRI before revascularization.

Improving diagnostic accuracy of MDCT coronary angiography in patients with mild heart rhythm irregularities using ECG editing.

OBJECTIVE: The objective of our study was to compare diagnostic accuracy of MDCT coronary angiography in a population of patients with mild heart rhythm irregularities before and after editing the ECG. SUBJECTS AND METHODS: Thirty-eight patients who underwent MDCT coronary angiography and conventional coronary angiography were enrolled in the study. The inclusion criterion was the presence of mild heart rhythm irregularities (i.e., premature beats; atrial fibrillation; mistriggering; or low heart rate, defined as 40 beats per minute or less) during the scan. All patients underwent MDCT with the following parameters: 16 detectors; collimation, 0.75 mm; gantry rotation time, 375 msec; 120 kV; and effective milliampere-second setting, 500-600. Images were reconstructed in two settings: before ECG editing and after ECG editing (i.e., arbitrary modification of temporal windows within the cardiac cycle at the site of mild heart rhythm irregularities). Data sets were scored for the presence of significant stenoses (> or = 50% lumen reduction) in coronary segments > or = 2 mm diameter. The results of the two groups were compared with a McNemar test, and a p value of less than 0.05 was considered significant. RESULTS: The sensitivity, specificity, and negative and positive predictive values of MDCT coronary angiography for the detection of significant stenoses before and after ECG editing were 63% (41/65) and 92% (78/85); 97% (251/260) and 96% (305/317); 87% (62/71) and 87% (81/93); 91% (251/275) and 97% (305/313), respectively (p < 0.05). The proportion of nonassessable segments was reduced from 17% (70/416) before ECG editing to 2% (10/416) after. CONCLUSION: ECG editing significantly improves diagnostic accuracy in a selected population of patients with mild heart rate irregularities.

Effects of primary angioplasty for acute myocardial infarction on early and late infarct size and left ventricular wall characteristics.

UNLABELLED: The effects of reperfusion on early and late infarct size and left ventricular wall characteristics were studied by performing cine-magnetic resonance imaging, first-pass perfusion, and delayed enhancement imaging in 22 patients at five days and five months after successful primary angioplasty for first acute myocardial infarction. Infarct size, end-diastolic wall thickness, and segmental wall thickening were quantified, and the extent of microvascular obstruction (MO) was evaluated qualitatively. Infarct size decreased by 31%. Segments without MO had early increased wall thickness and late partially normalized wall thickening. Segments with MO showed late wall thinning and no functional recovery at five months. OBJECTIVES: We aimed to study the effects of early successful primary angioplasty for ST-segment elevation acute myocardial infarction (AMI) on early and late infarct size and left ventricular (LV) wall characteristics. BACKGROUND: Early reperfusion treatment for AMI preserves LV function, but the effects on early and late infarct size, end-diastolic wall thickness (EDWT), and segmental wall thickening (SWT) are not well known. METHODS: In 22 patients with successful primary angioplasty for first AMI, cine-magnetic resonance imaging (MRI), first-pass perfusion, and delayed-enhancement imaging was performed at five days and five months. The extent of microvascular obstruction (MO) was evaluated on perfusion images. Infarct shrinkage was defined as the difference between the volume of delayed-enhancement at five days and five months. The EDWT and SWT were quantified on cine-MRI. RESULTS: Infarct shrinkage occurred to the same extent in small and large infarctions [r = 0.92; p < 0.001], with a mean decrease of 31% (35 +/- 21 g to 24 +/- 17 g). Dysfunctional segments without MO had an increased EDWT at five days compared with remote myocardium (9.2 +/- 1.7 mm vs. 8.4 +/- 1.7 mm; p < 0.001). At five months, EDWT in these segments became comparable to the thickness of remote myocardium (7.8 +/- 1.6 mm vs. 7.6 +/- 1.4 mm; p = 0.60), and SWT improved (21 +/- 15% to 40 +/- 24%; p < 0.001) but remained impaired (40 +/- 24% vs. 71 +/- 29%; p < 0.001). Segments with MO demonstrated wall thinning at five months (6.4 +/- 1.3 mm vs. 7.6 +/- 1.4 mm; p = 0.006) and no significant recovery in SWT (12 +/- 14% to 17 +/- 20%; p = 0.15). CONCLUSIONS: Infarct size decreased by 31%. Segments without MO had early increased wall thickness and late partial functional recovery. Segments with MO showed late wall thinning and no functional recovery at five months.